Adjusting wippen assist springs

Richard Brekne Richard.Brekne@grieg.uib.no
Sat, 13 Dec 2003 13:34:37 +0100


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Ok folks.... looks like I take the proverbial dive on this one... :)
Suffice to say that if my own insistent querying and illustration of my
(obviously erroneous) perspectives on this subject have helped prompt
the discussion to its present point, then that dive has been far from
for naught.

I do have a couple questions tho that are rather simplistic but require
a straight answer for myself, and perhaps any others who struggle with
the same kinds of misconceptions. The first is the one I asked yesterday
when Mark poimentenly punctured my balloon....


>> ... then I guess what you are both saying is that given 2 actions
>> one counterbalanced with lead to a 40 gram balance weight, and the
>> other lead free with a resulting 60 gram balance weight... that the
>> 60 gram action will play lighter as long as you are accelerating the
>> keys past the 9.8 m/s^2 mark.
>>
>

Secondly... I'm trying to put this idea of lead weights representing a
constant force (via the gravitational accelleration constant ??) into
clear view. Its easy enough to see that a whippen spring does  X amount
of work... say 10 grams and does no more no matter how hard you hit the
key. But I'm having a hard time digesting how the key leads can behave
in the same or similar constant fashion. With the present explaintion on
the  board... it would seem that as the keys accelleration gets closer
to 9.8 m/s^2 then the counterbalancing effect of the lead gets gradually
lessened, then becomes 0, and then becomes a load in itself actually
increasing the <<heavyness>>  [or force needed to accellerate further].
Doesnt that qualify as affecting the inertial response of the whole
thing, and isnt that gradual change rather propotional to the velocity
of the lead (and the rest of the key mass ?)

Re worded... The spring does x-grams of lifting...period. The
gravitational constant stays constant.. period... but the <<weight>> of
the lead changes with its velocity, and thereby, it would seem to me,
its counterbalancing effect would also change with velocity.

Then... how does that compare with the affect of the spring... which
dissapears first.. quickest.. If you were to graph this in terms of
Force (finger on the key) against Accelleration of the key... how would
the two compare ?

For those of you who've studied physics and have a very good working
familiarity with all this... these questions may or may not seem self
explanitory. Please remember then that there are a lot of readers at
various stages in their pursuit of understanding these things that have
similiar questions.

And over to something completely different... Sarah especially, Mark
too... I would like to thank for leading me through this discussion in
the exemplary fashion you did. Patiently, respectfully, and always with
a clear twinkle of humour in your words you took the time to find
misconception and straighten it out. Would that all with so much to
give, would learn to offer their help in such fine manner.

Cheers and Thanks
RicB


Grin... but I am still going to run that little experiement .... !

--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html


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